This invention relates in general to bearings and more particularly to a unitized bearing capable of taking radial loading as well as thrust loading in both axial directions.
While most single row tapered roller bearings are capable of accommodating thrust loading in only one axial direction, some are capable of taking the thrust loading in both axial directions. The latter are widely used in the rear axles of automobiles. The typical bearing having this capability, differs from the conventional single row tapered roller bearings in that it has a thrust rib at the large diameter end of the cup raceway and another thrust rib at the small diameter end of the cone raceway. Thus, conventional thrust loading is accommodated in the usual manner, that is the thrust load is transferred to the rollers at the raceways. However, when the thrust load is applied in the opposite direction, the rollers are compressed between the two ribs so that thrust load is transferred to the rollers through the ribs.
The thrust rib at the large diameter end of the cup is actually a separate ring which is detached during the initial assembly of the bearing, for otherwise it would be impossible to fit the conventional number of rollers between the cup and cone. Only after the rib ring, the cage, the rollers and the cone are assembled together is the cup fitted against the rib ring, and the two are usually clamped together in the housing in which the bearing is installed.
To prevent the bearing from falling apart during handling and installation into a bearing housing, it is desirable to retain the rib ring against the cup, even if only on a temporary basis. U.S. Pat. No. 3,420,589 of W. F. Green et. al. shows several ways of achieving this end. Perhaps the most popular method is to bond the rib ring to the cup with an adhesive. While this seems to be a relatively simple procedure, it is actually not since it necessitates a considerable amount of precision machining and other preparation. In particular, the opposing faces of the cup and rib ring must be perfectly flat and square which requires expensive machining operations. Also, to assure good adhesion, these faces must be ultrasonically cleaned. Then the adhesive must be applied, and this is usually a manual operation. Finally, the bearing must be placed in an oven to cure the adhesive. Aside from the foregoing, the inside diameter of the rib ring must be tapered to provide clearance for the metal cage. This is achieved during the initial machining of the rib ring, but is a costly operation since it involves machining a reverse taper, a procedure commonly referred to as back boring.